Buy a Z4MC.I don't. I am completely the opposite these days. I want cars as a 'hobby'. I do very little mileage nowadays but have always loved cars (and bikes). I now have the money I never had before and am a 'wannabe' car collector. Space is a problem and I am not a millionaire, though!
I have in writing from BMW heritage they are expecting it's trajectory to match that of the E46 CSL.
It's a baby CSL, more rigid, more fun, retro timeless looks. With your "little mileage" the value will only go up.
You have literally nothing to lose.
Bite the bullet and grab one, while you still can for that money.